The purpose of this study is to identify and differentiate variables believed to mediate the effects of natually-occurring non-traumatic separations of mother and infant during the first twelve months and to relate these variables to outcome measures of social-emotional functioning in the second year. The variables being studied are a) aspects of the separations themselves, b) characteristics of the substitute care provided, and c) contextual factors such as the reason for the separation and maternal attitudes about it. Data about separations, alternative care arrangements and maternal attitudes were obtained from 144 mothers during their baby's first year by interview. When the babies were approximately 15 months old, measures of the baby's response to strangers and attachement to mother were obtained in a standardized laboratory procedure. Analyses will relate aspects of separations, substitute care and contextual factor to outcome measures of social-emotional functioning.